Automatic video layouts for multi-stream multi-site telepresence conferencing system

ABSTRACT

A videoconference multipoint control unit (MCU) automatically generates display layouts for videoconference endpoints. Display layouts are generated based on attributes associated with video streams received from the endpoints and display configuration information of the endpoints. An endpoint can include one or more attributes in each outgoing stream. Attributes can be assigned based on video streams&#39; role, content, camera source, etc. Display layouts can be regenerated if one or more attributes change. A mixer can generate video streams to be displayed at the endpoints based on the display layout.

FIELD OF THE INVENTION

The present invention relates generally to videoconferencing systems,and more particularly to multi-stream, multi-site conferencing systems.

BACKGROUND

Videoconferencing entails exchange of audio, video, and otherinformation between at least two participants. Generally, avideoconferencing endpoint at each participant location will include acamera for capturing images of the local participant and a displaydevice for displaying images of remote participants. Thevideoconferencing endpoint can also include additional display devicesfor displaying digital content. In scenarios where more than twoendpoints participate in a videoconferencing session, a multipointcontrol unit (MCU) can be used as a conference controlling entity. TheMCU and endpoints typically communicate over a communication network,the MCU receiving and transmitting video, audio, and data channels fromand to the endpoints.

Telepresence technologies provide enhanced videoconferencing experienceto participants so that the near end participants feel as if they arepresent in the same room as the far end participants. Telepresencevideoconferencing can be provided for various conferencing systems,ranging from two person point-to-point videoconferencing systems tomulti-participant multipoint videoconferencing systems. Typically,telepresence utilizes multiple cameras to capture images of near endparticipants and multiple displays to display images of far endparticipants. Multiple video streams are transmitted from multipleendpoints to the MCU to be combined into one ore more combined videostreams that are sent back to the endpoints to be displayed on multipledisplay devices. For example, in a telepresence system involving threeendpoints, each endpoint having three cameras, the MCU will receive ninevideo streams. The MCU will have to combine the nine received videostreams into one or more combined video streams, which are sent back tobe displayed on the display devices at each endpoint. These nine videostreams will have to be laid out for each endpoint based on the numberand type of displays at each endpoint. Furthermore, although the MCU mayreceive the information from the endpoint that the current speaker islocated at that endpoint, with more than one video stream being receivedfrom each endpoint the MCU may not be able to determine which one of themultiple video streams includes the current speaker. Thus, dynamicallyselecting one of many video streams received from an endpoint forprominent display may be difficult.

Traditionally, for multi-point and multi-stream videoconferencingsystems, arrangement of video streams to be sent to each endpoint iscarried out manually. For example, video network operation centers, alsoknown as VNOC, offer manual management of telepresence videoconferencingthat includes appropriate layout of incoming video streams into combinedoutgoing video streams. The person managing the videoconference at theVNOC monitors the video streams for current speakers, and then manuallyarranges the layout so that the video stream having the current speakeris prominently displayed on the display screens at each endpoint.Prominently displaying the current speaker's image may involvemanipulating the scale and size of the displayed video stream. Again,the person managing the videoconference would manually carry out thescaling and sizing procedure. However, the manual management of VNOC canbe plagued by human errors and delays. Additionally, employing a humanoperator along with providing the required specialized training foroperating equipment can be very costly.

In summary, traditional approaches are plagued by static layoutarrangements of video streams or the necessity to use error prone manualcontrol if dynamic layout arrangement is desired.

SUMMARY

A continuous presence, telepresence, videoconference MCU is disclosedthat automatically generates layouts of video streams to be presented tovideoconference endpoints. A videoconference endpoint can include two ormore video cameras, at least one display device, coupled to a processor.The processor can include a codec for encoding video and audio streamsfor transmission and decoding received video and audio streams. Theprocessor can also include a stream attribute module for assigningattributes to outgoing streams. The endpoint can also include a speakerlocator for determining the location of a current speaker from among theparticipants. The processor can then determine the camera that capturesthe current speaker. Subsequently, the processor can instruct theattribute module to add an attribute to the video stream generated bythat camera, which attribute when examined by an MCU or another endpointcan indicate that the associated video stream includes the image of thecurrent speaker.

The attribute module can assign various attributes to a single videostream. Some attributes can be position based, specifying the positionof the camera that is the source of the video stream. For exampleposition based attributes can include “FR” (far right), “CL” (centerleft), etc. Some attributes can be role based, specifying the role ofthe participants included in the video stream. For example, role basedattributes can include “people,” “content,” etc. Role based attributescan have hierarchical classifications, such as, “people/audience,”“people/presenter,” etc. Video streams can be assigned more than oneattributes. For example, a video stream captured by the far right camerathat also includes the image of the current speaker can have attributes“FR” and “Speaker.” As another example, a video stream having the rolebased attribute “people/audience” can also have the “Speaker” attributeif one of the audience members is also the current speaker.

The MCU can include a layout manager and a mixer. The layout managergenerates layouts for video streams sent to each endpoint based on theattributes of incoming video streams and the configuration informationassociated with each endpoint. Such configuration information caninclude, for example, the number of display screens, the aspect ratio ofeach display screen, dedicated speaker display screen, etc. The mixercan combine video streams based on the layout determined by the layoutmanager. The combined streams can be transmitted to the appropriateendpoints. The layout manager monitors any changes in the attributes ofeach incoming video stream, the number of incoming video steam,configuration information of each endpoint, etc., and dynamically altersthe layout based on these changes.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be more readilyunderstood from reading the following description and by reference tothe accompanying drawings, in which:

FIG. 1 depicts an exemplary multipoint videoconferencing system;

FIG. 2 shows an exemplary videoconferencing endpoint;

FIG. 3 shows an exemplary videoconferencing system in which two or moreendpoints communicate with each other via an MCU;

FIG. 4A-4D shows various exemplary display layouts;

FIG. 4E illustrates exemplary layout data generated by the layoutmanager; and

FIG. 5 illustrates exemplary steps performed by the layout manager ingenerating video layouts.

DETAILED DESCRIPTION

FIG. 1 depicts an exemplary multipoint videoconferencing system 100.System 100 can include network 110, one or more multipoint control units(MCU) 106, and a plurality of endpoints A-E 101-105. Network 110 can be,but is not limited to, a packet switched network, a circuit switchednetwork, or a combination of the two. Endpoints A-E 101-105 may send andreceive both audio and video data. Communications over the network canbe based on communication protocols such as H.320, H.324, H.323, SIP,etc., and may use compression standards such as H.263, H.264, etc. MCU106 can initiate and manage videoconferencing sessions between two ormore endpoints. Generally, MCU 106 can mix audio data received from oneor more endpoints, generate mixed audio data, and send mixed audio datato appropriate endpoints. Additionally, MCU 106 can receive videostreams from one or more endpoints. One or more of these video streamsmay be combined by the MCU 106 into combined video streams. Videostreams, combined or otherwise, may be sent by the MCU 106 toappropriate endpoints to be displayed on their respective displayscreens. As an alternative, MCU 106 can be located at any one of theendpoints A-E 101-105.

FIG. 2 shows an exemplary endpoint 200 with multiple cameras andmultiple display devices. Cameras 202-205 capture images of the localparticipants present in the conference room, and can be arranged in arow to capture different portions of the conference room. Accordingly,cameras 202-205 can be labeled FR (far-right), CR (center right), CL(center left), and FL (far left). Of course, these labels are onlyexemplary. Different labels can also be used, for example, if camera 205is used to capture images of all participants then it can be labeled asWR (whole room). In another instance, camera 202 can be a pan-tilt-zoom(PZT) type camera that captures the image of the current speaker only,from among the local participants, and thus can be labeled CS (currentspeaker). Labels or attributes can be associated with the cameras andstored in memory in the processor 209.

Processor 209 can include a codec 210 for compressing and decompressingvideo and audio streams. For example, codec 210 can compress videostreams generated by cameras 202-205 to generate compressed videostreams, which can be transmitted to remote endpoints and/or an MCU.Additionally, codec 210 can decompress video streams received from theremote endpoints or the MCU, and display the video streams on displaydevices 206, 207, and 208. Codec 210 can include video codecs such asH.261 FCIF, H.263 QCIF, H.263 FCIF, H.261 QCIF, H.263 SQCIF, H.264,etc., and audio codecs such as G.711, G.722, G.722.1, G.723.1, etc.

Processor 209 can communicate with a speaker locator module 213, whichdetermines the location of the current speaker, i.e., the participantthat is currently speaking. Information provided by speaker locatormodule 213 can be used by processor 209 to determine which of thereceived video streams includes the current speaker. Speaker locatormodule 213 can employ a microphone array 224 that analyzes the soundreceived from a source, such as the current speaker, to determine thelocation of the current speaker with respect to the microphone array224. The microphone array 224 can include a series of spaced microphonesthat can be arranged horizontally, vertically, or in combination.Typically, at least one of the microphones in the array can be assignedas a reference microphone. A number of candidate locations can bepredetermined where the distance of the candidate locations from each ofthe microphones is known. Acoustic signals captured by each of themicrophones can be delayed with respect to the acoustic signal capturedby the reference microphone. This delay can be, in part, a function of acandidate source location and microphone location with respect to thereference microphone. Signal energies of each of the delayed signalsassociated with each candidate location can then be determined.Subsequently, the candidate location associated with the highest signalenergy can be selected as the location that best estimates the actuallocation of the audio source. In other words, using maximum likelihoodestimation, a predetermined candidate source that is likely to be thebest estimate of the actual location of the audio source can be selectedas the location of the audio source. Clearly, the accuracy of theestimation can improve with an increase in the number and spatialdistribution of the candidate locations. For example, 61 candidatelocations can be used at an approximate radial distance of 10 feet fromthe microphones. More details on determining locations of participantsusing microphone arrays are disclosed in commonly assigned U.S. Pat. No.6,912,178 entitled “System and method for computing a location of anacoustic source,” by Chu et al., and is hereby incorporated byreference.

Typically, the spatial relationship between the microphone array 224 andthe cameras 202-205 remains fixed. Therefore, location of the currentspeaker known with respect to the microphone array 224 can be readilytransformed into the location of the current speaker with respect to thecameras simply by changing the frame of reference. Each camera, with itsparticular pan-zoom-tilt settings, can capture a particular portion ofthe conference room, the boundaries of which portion can bepredetermined. Thus, the processor 209 can determine if the location ofthe current speaker, as expressed within the reference frame of thecamera, lies within the portion of the conference room captured by thatcamera. If the current speaker is located within the portion of theconference room captured by a camera, processor 209 can instruct thestream attribute module 212 to assign the attribute “Speaker” to thevideo stream generated by that camera.

Stream attribute module 212 can assign attributes to the outgoingstreams. These attributes can qualify the outgoing video stream in amanner that is useful for the MCU and/or the remote endpoint forrendering and displaying the video stream. These attributes can be addedto outgoing streams during transmission. For example, protocols such asH.323 and H.320 can be extended to include attribute definitions thatmay be used to label outgoing data streams. Video streams can havevarious attributes. For example, video streams can have positionalattributes that identify the relative location of the camera that is thesource of that video stream. As shown in FIG. 2, outgoing streams215-218 can have attributes that indicate the relative position of theirsource cameras. Stream 215, for example, is labeled “FR” because it issourced from the camera 202, which is placed in the far right (FR)position. Similarly, video stream 217 is labeled “CL” because its sourcecamera 204 is in a center left (CL) position.

Video steams can also have role based attributes such as “people” and“content.” Video streams can be labeled with “people” attribute if thevideo streams include images of people/participants. Role basedattributes can further have hierarchical classification. For example,where a number of participants in a video conference take turnspresenting information, classification of “people/presenter” and“people/audience” may be provided. A “people/presenter” attribute canindicate that the associated video stream includes images of people thatare to be prominently displayed irrespective of whether the video streamincludes a speaker or not. Video streams that contain digital content,such as presentations, can have a “content” attribute. For example,processor 209 receives data content from computer 224, which datacontent can include presentations, documents, videos, etc. Data contentcan be compressed and given the attribute “CON.” Although not shown, inFIG. 2, the endpoint can also include a dedicated data content display,which displays data streams received from MCU or remote endpoints.

Video streams can also have more than one attribute. For example, avideo stream can have both role based and “Speaker” attribute, such as“people/audience, Speaker,” “people/presenter, Speaker,” etc. The“Speaker” attribute can be assigned independent of the role of the videostream. For example, even if the current speaker is included in a videostream having the “people/audience” role, a “Speaker” attribute can beadditionally assigned to that video stream. As another example, videostreams can have both positional and “Speaker” attribute, such as, videostream 215—where in addition to having the “FR” attribute it can alsohave the “Speaker” attribute. As previously described, processor 209 candetermine which camera is capturing the current speaker. The processorcan then add the “Speaker” attribute to the video stream generated bythat camera. In the example shown in FIG. 2, the current speaker isbeing captured by camera 202; therefore, video stream 215 has theattribute “Speaker” associated with it. If the location of the currentspeaker changes, then the processor can reassign the “Speaker” attributeto the video stream that currently includes the current speaker. Forexample, if a different speaker begins to talk, and the image of thatcurrent speaker is captured by camera 204, then video stream 217 will beassigned the attribute “Speaker” in addition to the “CL” attribute.

Although only a single outgoing stream 215 of FIG. 2 is shown to havemultiple attributes, such multiple attributes can be assigned to morethan one stream. For example, stream 218 also can have multipleattributes such as “people/presenter” and “FL” assigned to it. Thus,video streams can be assigned one or more attributes, and the assignedattributes can be role based, camera position based, current speakerbased, or based on any other selected property. It is understood thatthe attributes shown in FIG. 2 can be encoded for transmission.

Video streams, data streams, and audio streams, along with theirattributes can be transmitted by the endpoint 200 to an MCU or a remoteendpoint via network 110. A transmitter/receiver 214 can serve as aphysical interface between the endpoint 200 and the network 110. Tx/Rx214 can also receive video streams from the MCU or remote endpoints. Forexample, video streams 219-221 are received by the processor 209. Videostreams 219-221 can include attributes that qualify the video streamsand can be used by the processor 209 for rendering or reproducing thevideo streams. For example, video stream 219 has attributes “R” and“Speaker.” Processor 209 can display video stream 219 on display device208, which is positioned to the right. Furthermore, because video stream219 has the “Speaker” attribute as well, the video stream may bedisplayed with more prominence. Likewise, video stream 220 withattribute “C” can be displayed on display device 207 and video stream221 with attribute “L” can be displayed on display device 206.

FIG. 3 shows an exemplary conferencing system 300 in which two or moreendpoints communicate with each other via an MCU 106. Endpoints 101,102, and 103 can be similar to the exemplary endpoint shown in FIG. 2.Each endpoint can have various configurations of cameras and displayscreens for providing a telepresence experience to their respectiveparticipants. For example, endpoint A 101 can include 4 cameras and 4display devices, endpoint B 102 can include 4 cameras and 3 displaydevices, while endpoint C 103 can include 1 camera and 2 displaydevices. Video streams can be exchanged between each endpoint and theMCU 106. For clarity, only video streams to and from endpoint A 101 havebeen shown in detail. MCU 106 can also include network interface 328,via which video, audio, and signaling data can be sent and received.

MCU 106 can include a layout manager 302 and a mixer 303. The layoutmanager 302 can determine display or video layouts, which include anarrangement of video streams sent to each endpoint. In determining videolayouts, the layout manager 302 not only determines which ones of thereceived video streams are to be sent to an endpoint, but also thespatial arrangement in which they are to be displayed. Thisdetermination can be based on the attributes associated with thereceived video streams and configuration information associated with theendpoint. The layout manager 302 can determine attributes associatedwith each video stream received by MCU 106. For example, attributes “FR,Speaker” 317, “CR” 318, “CL” 319, and “FL” 320 associated with videostreams 307, 308, 309, and 310 can be received from endpoint A 101.Similarly, video streams and their attributes can also be received fromendpoints B 102 and C 103 (denoted, for simplicity, by 315 and 316,respectively), and any additional endpoints. Configuration information329 received from each endpoint can include number of display devices,aspect ratio and resolution of display devices, existence of a dedicatedcurrent speaker display device, type of encoding used, etc. As will bedescribed with further detail below, the layout manager 302 can generatearrangement of video streams sent to each endpoint. This arrangement iscommunicated to the mixer 303 for execution by way of signal path 321.

Mixer 303 can receive video streams from one or more endpoints. Mixer303 can execute the arrangement of video streams determined by thelayout manager 302. For example, mixer 303 can receive video streamsfrom endpoints A 101, B 102, and C 103, combine the video streams basedon signals 321 received from the layout manager 302, and send combinedvideo streams back to each endpoint. Mixer 303 can include a codec 322for decoding incoming video and audio streams and encoding outgoingvideo and audio streams. For example, audio codecs can include standardcodecs such as, G.711, G.722, G.722.1, G.723.1, etc. Video codecs caninclude standard codecs, such as, H.261 FCIF, H.263 QCIF, H.263 FCIF,H.261 QCIF, H.263 SQCIF, H.264, etc. Codec 322 can also change theencoding scheme of outgoing audio and video streams based on theencoding scheme used at the receiving endpoint.

Mixer 303 can also include an image processing module 325 for carryingout manipulation of video frames received from various endpoints. Suchmanipulations can include combining two or more video frames into oneframe, scaling, cropping, overlaying, etc., more details of which aredisclosed in commonly assigned U.S. patent application Ser. No.12/581,626 entitled “System and method for combining a plurality ofvideo stream generated in a videoconference,” by Avishay Halavy, and ishereby incorporated by reference.

Mixer 303 can also include a stream attribute module 327 for assigningattributes to outgoing streams. For example, stream attribute module 327can assign attributes “FL”, “CL”, “CR, Speaker”, and “FR, CON” tostreams 311, 312, 313, and 314, respectively. The stream attributemodule 327 can receive instructions on which attributes to assign toparticular outgoing video streams from the layout manager 302.

MCU 106 can be compliant with the ITU standards, such as, but notlimited to, H.320, H.323, and H.324. Accordingly, the layout manager 302can be part of a media controller (MC), while the mixer 303 can be partof a media processor (MP). Mixer 303 can be implemented on applicationspecific integrated circuits (ASICs), microcontrollers, FPGAs,hardware/firmware combination, software running on microprocessors, etc.Various modules within the mixer 303, e.g., codec 322, Image processingmodule 325, and stream attribute module 327 can be individual hardwaremodules or can be software/firmware modules. Layout manager 302 can alsobe implemented separately as a hardware component such as amicrocontroller, ASIC, FPGA, hardware/firmware combination, software,etc.

FIG. 4A shows an example of the layout of images of various endpoints.In the example shown, the MCU 106 transmits video streams to anendpoint, say endpoint E, having four display devices 402, 404, 406, and408. The videoconference can include four other endpoints, say A, B, C,and D. The layout manager 302 can receive attributes associated withvideo streams generated by each of the five endpoints A, B, C, D, and E,and determine the layout of outgoing video streams to be displayed oneach of the display devices at each endpoint. Outgoing video streams canalso include attributes, which allow the endpoints to determine thedisplay device on which the video streams are to be displayed. Forexample, video streams received by endpoint E can include attributes,such as “FL” (far left display device), “CL” (center left displaydevice), “CR, Speaker” (center right display device) and “FR” (far rightdisplay device), etc. Outgoing video stream for each display device maybe a composite of video streams from multiple sources. The layoutmanager 302 can determine the number of “cells” to be displayed withineach display device, where the video displayed within a cell correspondsto a single source. For example, the combined video stream displayed ondisplay device 402 can be composed of four cells 421-424. Forillustration, the cells are labeled with the source assigned to them,such as A-FL (endpoint A, camera far left), A-CL (endpoint A, cameracenter left), B-FL (endpoint B, camera far left), and B-CL (endpoint B,camera center left). Of course, these labels are not displayed to theparticipants.

Endpoint E can also include one or more display devices for displayingonly the video streams that include the current speakers. Any displaydevices can be selected, however, display device 406 has been shown asan example. As mentioned previously, the layout manager 302 candetermine which of the incoming video streams includes the speaker basedon the attributes associated with each video stream. The layout manager302 can then arrange that video stream such that it is displayed on theparticular display device reserved for the video stream including thecurrent speaker in addition to arranging the same video stream such thatit is displayed in a cell on one of the other display devices. Forexample, in FIG. 4A, the video stream received from the center-leftcamera at endpoint A includes the current speaker. Layout manager 302can include the video stream in cell 422 of the video stream displayedon display device 402 in addition to having only that video stream alsobeen displayed on the display device 406 (note that image ofparticipants in cell 422 has been shaded merely for indicating that theassociated video stream includes the speaker).

The layout manager 302 can also dynamically arrange the output streamsin response to changes in the attributes of the input streams. Forexample, if the current speaker changes from one video stream toanother, the layout manager 302 can rearrange the output streams toreflect this change. As shown by way of example, in FIG. 4B, the currentspeaker is now located in the video stream of the left camera atendpoint D. This video stream can have the attribute “Speaker”associated with it, which attribute can be detected by the layoutmanager 302. Consequently, the layout manager can rearrange the outputstreams so that the video stream directed to the display device 406 isthe video stream received from the left camera at endpoint D, replacingthe previously displayed video stream from center-left camera ofendpoint A.

The layout manager 302 can provide continuous presence experience to theconference participant. In other words, the conference participant canview video streams from all endpoints simultaneously, and not just fromthe endpoint that includes the current speaker. For example, referringto FIG. 4A, even though the current speaker is located at endpoint A,the participant at endpoint E can receive video streams from each of theother participating endpoints A, B, C, and D. Additionally, theconference participant can view video streams of participants other thanthe current speaker. For example, if the current speaker is at endpointA, then the participants at endpoint E can see video streams capturingimages of other participants in addition to the video stream capturingthe current speaker. Furthermore, even when the location of currentspeaker changes from one endpoint to another (e.g., from endpoint A toendpoint D), the layout manager 302 still maintains continuous presencedisplay of video streams.

FIG. 4C shows an exemplary layout of video streams when one of theendpoints has a dedicated speaker camera. For example, endpoint C caninclude at least two cameras: one for capturing the whole room, andanother for capturing the current speaker in the room. The cameracapturing the whole room can be a wide angle camera, while the cameracapturing the speaker only can be a pan-tilt-zoom camera. Note that anendpoint can include a speaker locator module (e.g., FIG. 2, 213) thatdetermines the location of the current speaker. The processor can usethis location information to control the PTZ camera so that the camerapredominantly captures the image of the current speaker. The streamattribute module of the endpoint can assign an attribute “C-WR” to thevideo stream of the camera capturing the whole room while assign theattribute “C-Speaker” to the video stream of the PTZ camera. Uponreceiving these video streams from endpoint C, the layout manager 302 ofMCU 106 can assign the video stream with “C-WR” attribute to cell 481,while assign the video stream with “C-Speaker” attribute to the displaydevice 406.

In comparison with FIGS. 4A-4C, in which the display screen 406 wasreserved to display only the current speaker and in which the videostream sent to the display device 406 was not divided into cells, theexample shown in FIG. 4D can include multiple cells showing digitalcontent in addition to a current speaker. The video stream sent todisplay device 406 can include three cells 461, 462, and 463. Cell 461can include a data content video stream, which data content can includepresentations sourced from, e.g., a computer at one of the endpoints.Cells 462 and 463 can include images of the last two current speakers.One or the cells 462 or 463 may display a video stream having theattribute “people/presenter,” which indicates that the associated videostream should always be prominently displayed.

FIG. 4E illustrates exemplary layout data that the layout manager 302can generate and send to the mixer 303. Mixer 303 can use this data togenerate outgoing streams for endpoints participating in the videoconference. As an example, FIG. 4E shows layout data corresponding tothe display layout depicted for display screens 402 and 406 in FIG. 4A.It is understood that layout data for other streams for the sameendpoint E, as well as layout data for other streams for other endpointscan be similarly generated.

Layout data 490 includes several parameters that the mixer 303 can useto mix video streams. For example, the frame size indicates the numberof horizontal and vertical pixels in each frame of stream 1. The layoutmanager 302 can determine the frame size based on the resolution of thedisplay screen. Information on resolution is typically received asconfiguration information from endpoint E. So if the resolution of thedisplay screen were 720×1280, then the layout manager 302 may select720×1280 as the frame size. The No. of cells field defines the number ofportions in which the frame is divided into. For example, referring toFIG. 4A, the frame displayed on display device 402 is divided in 4 cellsof equal size and arranged in two rows and two columns (2×2). The cellsize indicates each cell size in pixels. In instances where the cellsare of unequal sizes, the cell size field can include additional cellsizes corresponding to each cell. The next field indicates the sourcestream for each cell within the frame. In this example, the top twocells, cell 1 and cell 2 (corresponding to portions 421 and 422 in FIG.4A), are assigned video streams received from endpoint A and havingattributes FL and CL, respectively. The layout manger 302 can alsoassign an attribute to the outgoing stream so that the receivingendpoint E can determine the display device on which this video streamis to be displayed, for example, on the far left (FL) display device402. Layout data 491 can correspond to the layout of video streams ondisplay device 406 of FIG. 4A. Because display device 406 is dedicatedto display only one video stream (that includes the current speaker),the frame includes only a single cell. The layout manager can assign anattribute so that the endpoint can display stream 2 on the center right(CR) display device 406.

The layout manager 302 can send layout data (e.g., 490 and 491) to mixer303 via signal path 321. The layout manager 302 can also store thelayout data in memory that can be accessed by the mixer 303. Such memorycan include registers, RAM, etc. Mixer 303 can access layout datarepeatedly to check if the layout data has changed. Alternatively, thelayout manager 302 can set a flag or cause and interrupt each time thereis any change in the layout data or if the memory is updated.

FIG. 5 shows an exemplary flowchart detailing the steps that can beperformed by the layout manager 302 in determining the layout of videostreams on the display devices at one endpoint. The layout manager 302can perform similar steps for determining the layout of each of theother endpoints participating in the videoconference. In step 501, thelayout manager 302 can receive attributes associated with each incomingvideo streams from all endpoints participating in a videoconferencingsession. In step 502, layout manager 302 can determine the number ofdisplay devices at the endpoint. Information regarding the number ofdisplay devices and their properties can be received in real time in theform of configuration information. Such information can also be storedin memory at the MCU 106.

In step 503, the layout manager 302 can determine if the number ofincoming streams to be displayed at the endpoint E exceeds the number ofdisplay devices at endpoint E. If the number of incoming streams to bedisplayed at endpoint E is less than or equal to the number of displaysat endpoint E, then potentially, each display device can display asingle video stream. Thus, the MCU 106 may not need to combine two ormore video streams into one video stream. For example, if endpoint Ewere to have four display devices and is in a videoconferencing sessionwith three other endpoints, each generating a single video stream, thenthe layout manager 302 can associate three display devices at endpoint Ewith the three other endpoints' video streams. The fourth display devicecan be assigned to receive the video stream that includes digitalcontent or the video stream that includes the current speaker. Once thelayout manager 302 assigns video streams to particular display devices(in step 504), the layout manager 302 can add attributes to the outgoingstreams (in step 509). Such attributes can include the relative positionof the display device on which the video stream is to be displayed,whether the video stream includes digital content, speaker, etc.

If the number of video streams to be displayed at endpoint E is greaterthan the number of display devices available, then two or more videostreams can be combined into one video stream. Layout manager 302 cancheck if any of the display devices at endpoint E are dedicated todisplaying only the current speaker. If yes, then the video stream withand attribute “Speaker” can be directed to that display device (step505). The remaining display devices can be used to display the remainingvideo streams.

As an example, the number of cells per display device can be determinedby dividing the total number of video streams to be displayed by thenumber of available display devices. But other factors, such as aspectratios of the video streams and the display devices, the amount ofacceptable downscaling of the video streams, etc., can also beconsidered in determining the number and size of the cells. Referring tothe example shown in FIG. 4A, the layout manager 302 can determine thatone of the display devices, 406, at endpoint E is reserved fordisplaying the video stream that includes the current speaker.Therefore, there are three display devices—402, 404, and 408—fordisplaying 11 video streams from endpoints A, B, C, and D. The layoutmanager 302 can divide the display area for two of the display devicesinto four cells, while divide the display area of the remaining displaydevice into three cells. It is understood that this method ofdetermining the number of cells per display device is only exemplary,and that other methods can also be envisioned.

In step 507, layout manager 302 can assign video streams to cells. Ifthe video streams are of the same format and do not have any spatialinter-relationship, then the layout manager 302 can loosely assign avideo stream to any cell. For example, the layout manager 302 can assignall video streams from one endpoint to cells within a single displaydevice. But generally in videoconferencing—and particularly intelepresence videoconferencing—video streams received by the MCU 106from an endpoint can represent portions of a complete image of theconference room, which video streams when displayed side-by-side canreproduce the image of the complete conference room. For example,referring to FIG. 4A, layout manager 302 can arrange 4 video streamsreceived from endpoint A side-by-side in four cells 421, 422, 441, and442, where cells 421 and 422 belong to one display device 402 whilecells 441 and 442 belong to the adjacent display device 404. As aresult, video streams from one endpoint can be distributed over multipledisplay devices. In other words, spatial relationship of displayed videosteams can extend over multiple display devices. In a similar fashion,four video streams from endpoint B can be assigned to cells 423, 424,443, and 444. Likewise, two video streams from endpoint B can beassigned to cells 482 and 483, while the single video stream fromendpoint C can be assigned to cell 481.

Once incoming video streams have been assigned to their cells, thelayout manager 302 can instruct the mixer 303 to combine video streamsassigned to cells of the same display device (step 508). For example,referring to FIG. 4A, the four video streams labeled “A-FL,” “A-CL,”“B-FL,” and “B-CL” associated with cells 421, 422, 441, and 442,respectively, can be combined into a single video stream. A combinedvideo stream can have attributes that allow the receiving endpoint todetermine which display device the combined video stream is to bedisplayed. For example, the combined video stream of video streams fromcells 421, 422, 441, and 442 can have an attribute “FL” indicating thefar left display device 402. In step 509, the layout manager 302 caninstruct the mixer 303 to add attributes to the outgoing combined videostreams. Attributes can also be added to video streams that are not aresult of a combination of other video streams (as resulting from step504).

Having configured the layout of outgoing video streams to each endpoint,the layout manager 302, in step 510, can monitor any change inattributes of the received video streams and/or change in the number ofvideo streams. For example, if the attribute “Speaker” previouslyassociated with one incoming video stream is now associated with adifferent incoming video stream, the layout manager 302 can detect thischange, and reconfigure (in steps 503-509) the layout of the outgoingstreams so that the video stream currently having the attribute“Speaker” is displayed appropriately at each endpoint. For example,referring to FIGS. 4A and 4B, when the “Speaker” attribute, previouslyassociated with the video stream received from the center left camera ofendpoint A (A-CL) is now associated with the video stream from the leftcamera of endpoint D (D-L), the layout manager 302 can reconfigure thelayout so that video stream sent to the dedicated speaker display 406 ischanged from A-CL to D-L. Additionally, if the number of incoming videostreams from the participating endpoints changes, for example, when anendpoint exits a videoconference session, the layout manager 302 candetect this change, and reconfigure the outgoing video streams. Thus,the layout manager can provide dynamic reconfiguration of video streamlayouts.

The above description is illustrative and not restrictive. Manyvariations of the invention will become apparent to those skilled in theart upon review of this disclosure. The scope of the invention shouldtherefore be determined not with reference to the above description, butinstead with reference to the appended claims along with their fullscope of equivalents.

What is claimed is:
 1. A method for generating display content for anendpoint communicating over a network with at least one other endpointcomprising: generating a display layout automatically for the endpointbased on attributes associated with video streams received from the atleast one other endpoint and display-configuration information of theendpoint, wherein display-configuration information includes at least anumber of display devices at the endpoint, wherein generating thedisplay layout comprises: generating a plurality of cells, and assigningvideo streams received from the at least one other endpoint to theplurality of cells, wherein one video stream is assigned to one cell;and mixing received video streams based on the display layout togenerate one or more video steams for the endpoint, wherein mixingfurther comprises combining video streams associated with the pluralityof cells to form an outgoing video stream; and wherein the displaylayout preserves a spatial relationship between at least two of thevideo streams received from the at least one other endpoint.
 2. Themethod of claim 1, wherein the display layout is a continuous presencelayout.
 3. The method of claim 1, wherein at least one video stream hasmore than one attribute associated with it.
 4. The method of claim 1,further comprising dynamically regenerating the display layout inresponse to a change in any one of the attributes.
 5. The method ofclaim 1, wherein generating a display layout comprises identifying afirst video stream received from a first of at least one other endpoint,the associated attribute of which indicates that the first video streamincludes an image of a first current speaker.
 6. The method of claim 1,wherein generating the display layout further comprises assigning thefirst video stream to an outgoing video stream, and assigning anattribute to the outgoing video stream, the attribute indicating thatthe outgoing video stream includes an image of a current speaker.
 7. Themethod of claim 3, wherein generating the display layout furthercomprises identifying a second video stream received from a second of atleast one other endpoint, the associated attribute of which indicatesthat the second video stream includes an image of a second currentspeaker, and assigning the second video stream to the outgoing stream.8. The method of claim 1, wherein at least two of the plurality of cellsare spatially arranged in such a way that the arrangement preserves aspatial relationship between at least two of the associated videostreams received from the at least one other endpoint.
 9. Avideoconferencing multipoint control unit (MCU) for managingvideoconferencing between an endpoint and at least one other endpoint,comprising: a layout manager configured to automatically generate adisplay layout for the endpoint based on attributes associated withvideo streams received from the at least one other endpoint anddisplay-configuration information of the endpoint, thedisplay-configuration information including at least a number of displaydevices at the endpoint, wherein the layout manager is configured togenerate the display layout by generating a plurality of cells, andassigning video streams received from the at least one other endpoint tothe plurality of cells, wherein one video stream is assigned to onecell; and a mixer communicably coupled to the layout manager andconfigured to mix received video streams based on the display layout togenerate one or more video steams for the endpoint, wherein the mixer isconfigured to combine the video streams associated with the plurality ofcells to form an outgoing video stream; and wherein the display layoutpreserves a spatial relationship between at least two of the videostreams received from the at least one other endpoint.
 10. The MCU ofclaim 9, wherein the display layout is a continuous presence layout. 11.The MCU of claim 9, wherein at least one video stream has more than oneattribute associated with it.
 12. The MCU of claim 9, wherein the layoutmanager is configured to regenerate the display layout in response to achange in any of the attributes.
 13. The MCU of claim 9, furthercomprising: a stream attribute module communicably coupled to the layoutmanager and configured to determine attributes associated with videostreams, wherein the stream attribute module identifies a first videostream received from a first of at least one other endpoint, theassociated attribute of which indicates that the first video streamincludes an image of a first current speaker.
 14. The MCU of claim 13,wherein the layout manager is configured to assign the first videostream to an outgoing video stream, and wherein the stream attributemodule is configured to assign an attribute to the outgoing videostream, the attribute indicating that the outgoing video stream includesan image of a current speaker.
 15. The MCU of claim 14, wherein thestream attribute module identifies a second video stream received from asecond of at least one other endpoint, the associated attribute of whichindicates that that the second video stream includes a second currentspeaker, and wherein the layout manager assigns the second video streamto the outgoing video stream.
 16. The MCU of claim 9, wherein the MCU islocated at the endpoint.
 17. The MCU of claim 9, wherein the layoutmanager is configured to spatially arrange at least two of the pluralityof cells in such a way that the arrangement preserves a spatialrelationship between at least two of the associated video streamsreceived from the at least one other endpoint.